7.2.1 Haruffa na Lines
Yanzu, ba batun amfani da nau'ikan layi daban-daban ba ne ga abubuwa ba tare da wani ma'auni ba. A zahiri, kamar yadda kuke gani daga sunaye da kwatancen layin layi a cikin taga Mai sarrafa Linetype, yawancin layin layi suna da takamaiman takamaiman dalilai a fagage daban-daban na zanen fasaha. Misali, a cikin zanen injiniyan farar hula, nau'in layin na iya zama da amfani sosai don nuna kayan aikin gas. A cikin zane-zane na injiniya, ana amfani da layin ɓoye ko tsakiya akai-akai, da dai sauransu. Misalai masu zuwa suna nuna wasu nau'ikan layukan da amfaninsu a zanen fasaha. A haƙiƙa, mai amfani da Autocad dole ne ya san abin da ake amfani da nau'ikan nau'ikan daban-daban dangane da yankin da aka zana, tunda sun ƙunshi duka haruffan layi.
